The present invention relates generally to vehicle wheel service procedures, and in particular, to a method for providing a visual display of information to an operator to direct a manual controlled movement of one or more vehicle wheels or vehicle components.
During a vehicle service procedure, an operator is occasionally required to manually move a vehicle wheel or vehicle component at a controlled speed while measurements are acquired. This movement may be a rolling movement of the entire vehicle, such as during a rolling compensation procedure, steering movement of the steered vehicle wheels, such as during acquisition of vehicle wheel alignment angle relationship data, or rotational movement of a single wheel such as a slow-speed rotation of a wheel assembly on a vehicle wheel balancer during a rim runout procedure. During a vehicle bump steer measurement procedure, an operator may be required to raise and lower the vehicle body, to load and unload the vehicle suspension, at a rate which is suitable for data acquisition.
In each case of controlled movement of a vehicle component, it is generally desirable that the rate of movement fall within a specific tolerance range to enable various associated sensors to acquire sufficient measurement data to complete the procedure. Unguided manual movement of the wheel or component by an operator can be very erratic, and accordingly, it would be advantageous to provide an operator with a visual display to guide the operator to maintain the rate of movement within the tolerance range of the desired movement rate.
For example, during a vehicle wheel alignment process, the operator is occasionally required to carry out steered-wheel alignment angle adjustments for wheel alignment angles which are measured with the vehicle steered in a straight-ahead direction, but which are physically easier to adjust with the wheel in a steered-in or steered-out position. To avoid the necessity of repeatedly returning the steered wheel to the straight-ahead position to check the progress of adjustments, it is necessary to determine a relationship between the alignment angle being adjusted and the vehicle wheel steering angle. For example, measured camber and caster angles vary in relationship to the current steering-angle (toe angle) measurement.
To determine this relationship during a caster angle measurement procedure, it is conventional for a steered wheel of the vehicle to be steered to either the left or right at 10°+/− a predetermined tolerance, or to 20°+/− a predetermined tolerance. The measurements required to calculate the measured caster angle are obtained during a caster steer procedure, and are based on either changes in the camber angle of the wheel or, for some machine-vision based alignment systems utilizing the Schur method of calculating caster, on a minimum of two different images of the wheel or target as the toe angle of the wheel changes. Specification values for camber and caster angles are typically defined only for a specific steering-angle (toe angle), such as 0° toe, or with the steering-angle (toe angle) aligned relative to the vehicle thrust line.
Often it is difficult or awkward for the operator to maintain the vehicle steering in a specified steered location (i.e., 10° or 20°) and access the various suspension components and adjustment points required to complete the necessary alterations. Additionally, during a vehicle wheel alignment adjustment procedure, any steering angle changes are typically made by turning the vehicle steering wheel from the driver's seat position, and not by turning the vehicle wheels directly, resulting in lost time to complete the alignment adjustment procedure, additional physical effort, and an inconvenience to the alignment technician who is required to climb in and out of the vehicle.
For some wheel alignment angle adjustments, the operator is required to initially steer the vehicle wheels to a straight ahead (or 0°) position, or to another predetermined position, from the driver's seat, make the necessary adjustments causing the steered location of the vehicle wheels to change, and then return to the driver's seat to steer the wheels back to the predetermined position to continue making adjustments of the alignment angles. This time consuming process is repeated several times until the adjustments of the alignment angles results in the alignment angles being within specification while the vehicle is steered to the predetermined position.
Furthermore, when the operator turns the steered wheel from the straight-ahead or predetermined position, the measured value for the steering-angle sensitive alignment angle, such as camber or live caster, will change in relationship to the steered angle of the vehicle wheel. If the operator attempts to adjust the steering-angle sensitive alignment angle with the wheel steered away from the straight ahead or predetermined position, using the measured value associated with the straight-ahead or predetermined steered position, the resulting adjustment will be incorrect when the wheel is returned to the straight-ahead or predetermined steered position.
Accordingly, methods for compensating steered-angle sensitive wheel alignment angle measurements for the effects of steering a wheel away from a straight ahead or predetermined measurement position have been developed, such as shown and described in U.S. Published Application No. 2006-0080015 A1 which is herein incorporated by reference, thereby enabling an operator to carry out a vehicle wheel alignment angle adjustment without having to maintain a wheel in a straight-ahead or other predetermined steered condition during an alignment angle adjustment, or requiring the operator to continually return the wheel to the straight-ahead or predetermined position to acquire updated measurements of an alignment angle during the adjustment thereof.
To acquire sufficient measurement data to compensate steered-angle sensitive wheel alignment angle measurements, it is necessary for an operator to steer the vehicle wheels through at least an arc of a minimum range, at preferably a controlled rate of speed suitable for acquisition of measurement data at a desired rate. Different types of vehicle wheel alignment systems will acquire measurement data at different rates. For example, a machine-vision vehicle wheel alignment system may acquire alignment measurement data at a rate which is proportional to the rate at which the system is capable of processing images of the wheels, requiring a slow rate of steer, while a system utilizing gravity-reference angle transducers may have a much higher data acquisition speed, allowing a faster rate of steer. Furthermore, given that different vehicles have different steering gear ratios, different size steering wheels, and different wheel assembly sizes, it is difficult for an operator to consistently steer the vehicle wheels about the required arc at the desired rate of speed.
Accordingly, it would be advantageous to provide an operator with information which facilitates the ability to manually steer the vehicle wheels at the desired rate of speed and in a desired direction over the required steering range. This information may be in any suitable form, such as an audible signal or visual display.
Additional advantages may be achieved by providing an operator with a visual display of information which facilitates the ability to manually roll the vehicle wheels at a desired speed and in a desired direction over a required distance during a vehicle wheel alignment procedure. Either concurrently or alternatively, an audible signal may be provided which varies in a discernable manner, such as in tone, pitch, or volume to indicate a direction and/or speed of movement of the vehicle wheels.
Similar advantages may be realized by providing an operator with a visual display of information which facilitates the ability to manually rotate a vehicle wheel assembly mounted on a vehicle wheel balancer at a desired rotational speed and in a desired direction during a vehicle wheel assembly measurement procedure. Either concurrently or alternatively, an audible signal may be provided which varies in a discernable manner, such as in tone, pitch, or volume to indicate a direction and/or rotational speed of movement of the vehicle wheel assembly.